GRx\PTOLITES OF NEW YORK. PART 1 (505 



Remarlcs. The fact that the rhabdosomes of this species in the usually 

 compressed state [fig.20] appear to be derived from a flabelliform colony, led 

 to the early view that these organisms had been flal)elliform, like gorgonias. 

 Brogger was able to show for D. f label lif or m e that its rhabdosome 

 was actually funnel-shaped, by finding specimens where the upper and lower 

 parts of the rhabdosome are not lying in the same bedding plane and are 

 separated by a thin layer of shale SJoc. cit. tab.l2, fig. 18]. Such specimens 

 have been also found among the Schaghticoke material, Avhere the upper 

 half is partly broken away and the lower half is exposed in its ^Dlace. 

 The early growth stages, and specially such obliquely compressed specimens 

 as those figured on plate 1, figures 16-19, leave no doubt that a cup-shaped 

 arrangement of the branches took place from the beginning. 



Brogger describes a variety of D . f 1 a b e 1 1 i f o i" m e as var, c o n - 

 f e !• t \i m Linnarsson ms. and a mutation, D. f 1 ab e 1 1 i f or m e mut. 

 norvegicum (I), norvegicum Kjerulf), The variety confer turn 

 is said to have a much finer and closer network, and its transverse dis- 

 sepiments I'emain always very thin. The mutation norvegicum is 

 characterized by short angular meshes and thick dissepiments. It occurs at 

 Vakkero near Christiania in a higher bed than the typical form. Matthe^^" 

 records [1892, p.36] that the variety c o n f e r t u m appears to be particularly 

 common in the lower beds at St John containing Dictyonema, and adds that 

 it is distinguished from the typical form, found at a higher level, by its 

 vasiform shape. The same author also refers a form which he found 

 in the middle and upper Dictyonema bed with some doubt to 

 D . norvegicum; and describes the principal form of St John as 

 var. a c a d i c u m , stating that it differs from the typical Swedish D . f 1 a - 

 b e 1 1 i f o r m e by having inore numerous thecae on its branches, namely 1 6 

 to 17 in 10 mm against 10 to 15 of the typical form. 



As Brogger suggests it is questionable, on account of the great multi 

 plicity of variations and transitions, whether these varieties can be kept apart. 

 This has also been the experience of the writer with the New York material. 

 In this, fragments bearing the characters of c o n f e r t u m and nor- 



